<template>
    <div>
        Child
        <button @click="handleClick">click</button>
    </div>
</template>

<script>
export default {
    methods: {
        handleClick() {
            console.log(this.$parent.parentTitle);
            console.log(this.$parent.$parent.appTitle);
            console.log(this.$root.appTitle);
        }
    }
}
</script>